The effects of Vernonia amygdalina(Asteraceae) Delile methanolic leaf extract on markers of oxidative stress in mice treated with high doses of acetaminophen
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Oxidative stress has been associated with many diseases, causing injury on cells, tissues and organs. Due the complications associated with it, conventional medicines have used antioxidants like minerals and vitamins in its management. Several plants have been shown to be rich in substances that possess antioxidant properties and have thus been used in the treatment of many ailments. To determine the effects of methanolic leaf extract of Vernonia amygdalina Delile on Total antioxidant capacity and malondialdehyde levels in mice treated with toxic doses of acetaminophen. The leaves of local varieties of Vernonia amygdalina Delile were extracted with 80% methanol, concentrated, dried and re-dissolved in distilled water for use. White albino mice of either sex, weighing between 20 – 31g were randomly separated into 6 groups of 6 mice each. 300 mg of acetaminophen was administered orally to all the groups except group 1(negative control) which received normal saline at 2ml/kg and group 2 (extract only). This was followed by administration of Vernonia amygdalina Delile extract to groups 2 and 4 at 50 mg/kg and group 5 at 100 mg/kg, while group 6 was given Vitamin C at 500 mg/kg, all treatments were given orally. After 8 hours blood samples were collected by cardiac puncture, the livers were excised from the animals, homogenised and centrifuged to obtain a supernatant. Whole blood and supernatant of liver were used for biochemical analysis, using Ferric Reducing Antioxidant Power Assay (FRAP) for Total antioxidant capacity and Thiobarbituric-Acid reactive substances (TBARS) Assay for estimating malondialdehyde levels. The results for the Total antioxidant capacity were compared by One-way analysis of variance, while Kruskal Wallis H test was used for the malondialdehyde levels; then these were followed by Turkeys HSD Post Hoc Test, with p ˂ 0.05 considered significant. The administration of Vernonia amygdalina Delile, methanolic leaf extract produced an increase in the total antioxidant capacity, Group1 (negative control) [mean blood 0.75U/mg, liver 0.81U/mg] as compared to Group 3 (positive control) [mean blood 0.54U/mg, liver 0.49U/mg, p=0.001]; Group 4 (acetaminophen + Vernonia amygdalina low dose) [mean blood 0.64U/mg, liver 0.68U/mg, p=0.001] ; Group 5 (acetaminophen + Vernonia amygdalina high dose) [mean blood 0.70U/mg, liver 0.77U/mg, p=0.001]; and Group 6 (acetaminophen + vitamin C)) [mean blood 0.69U/mg, liver 0.75U/mg, p=0.001], and a reduction in the malondialdehyde levels Group1 (negative control) [mean blood 0.75U/mg, liver 0.81U/mg] as compared to Group 3 (positive control) [mean blood 0.54U/mg, liver 0.49U/mg, p=0.001]; Group 4 (acetaminophen + Vernonia amygdalina low dose) [mean blood 0.64U/mg, liver 0.68U/mg, p=0.001] ; Group 5 (acetaminophen + Vernonia amygdalina high dose ) [mean blood 0.70U/mg, liver 0.77U/mg, p=0.001]; and Group 6 (acetaminophen + vitamin C ) [mean blood 0.69U/mg, liver 0.75U/mg, p=0.001]. In conclusion, the study showed that the methanolic leaf extract of Vernonia amygdalina Delile possesses significant antioxidant properties allowing it to attenuate oxidative stress and lipid peroxidation processes, thus this high antioxidant capacity justifies its use in folk medicine in the treatment of oxidative stress associated diseases like diabetes. This study has also contributed to the scientific validation of the antioxidant properties of Vernonia amygdalina plant growing in Zambia.
The University of Zambia
THESIS MSC (PHARMACOLOGY)